Technical Field
The present invention relates to a terminal with a wire which includes an anticorrosion portion formed at a connection portion of heterogeneous metals in a wire and terminal metal fitting, a manufacturing method of the terminal with the wire, and a wire harness containing the terminal with the wire.
Related Art
For example, a wire harness is routed in a vehicle in order to electrically connect devices mounted in the vehicle. The wire harness is configured to include wire bundles and various types of connectors provided at the ends of the wire bundles. The connector of the wire harness is configured to include an insulative connector housing and a plurality of conductive terminal metal fittings contained in a terminal housing chamber of the connector housing. The terminal metal fitting is provided at the end of a wire of the wire bundle. As the wire, a copper wire (a conductor is made of copper or copper alloy in a twisted form) is generally used. Then, after the end of the copper wire is stripped, the copper wire is crimped by the terminal metal fitting and connected thereto. Further, the terminal metal fitting has a copper or copper alloy base material as the conductor of the copper wire, and may be plated.
In recent years, an aluminum wire (“aluminum wire” in this specification means an aluminum or aluminum alloy conductor) has been used in place of the copper wire in consideration of reduction in weight of a vehicle and ease of recycling materials in addition to shortage of copper resources. However, it is known that an oxide film formed in the aluminum wire is thick compared to a copper material of the copper wire. Further, it is known that the aluminum wire tends to have a relatively-high contact resistance between the conductor and the terminal metal fitting (a crimp terminal). Therefore, there is employed a method of increasing a compression ratio by strongly caulking the conductor using a pair of conductor caulking pieces formed in the crimp terminal in order to decrease the contact resistance between the conductor of the aluminum wire and the crimp terminal. According to the method, the oxide films of element wires of the conductor can be destructed by strongly caulking the conductor of the aluminum wire. In other words, the contact resistance between the conductor and the crimp terminal can be decreased.
However, it is known that, when moisture is present in the contact portion, both aluminum and copper are ionized and melt into the water so as to cause a potential difference therebetween. Therefore, electrolytic corrosion occurs in a contact portion between an aluminum material and a copper material (in other words, the contact portion of heterogeneous metals). Further, when the conductor of the aluminum wire and the copper or copper alloy crimp terminal are electrically and mechanically connected, a crimp portion of the conductor by the conductor caulking piece of the crimp terminal is crimped at a high compression. Therefore, the moisture is prevented from entering and, as a result, the occurrence of the electrolytic corrosion is avoided. However, since the conductor is partially exposed at a position in an axial direction (an extension direction of the wire) of the terminal with respect to the crimp portion of the conductor by the conductor caulking piece (an extension direction of the wire), the moisture is attached thereto and reaches up to the crimp portion. Then, the crimp portion comes into a state like dipping in an electrolytic solution, thereby dissolving the aluminum of a highly ionizing tendency and progressing the electrolytic corrosion. Therefore, in order to prevent the moisture from being attached to the exposed portion of the conductor and from entering the crimp portion, an anticorrosion portion 115 (sealing portion) illustrated in FIGS. 13A and 13B is formed in the related art (for example, see Patent Literature 1).
In FIGS. 13A and 13B, the reference numeral 101 indicates an aluminum wire, and the reference numeral 102 indicates a crimp terminal. The aluminum wire 101 is configured to include an aluminum or aluminum alloy conductor 103 and an insulative resin covering member 104 covering the conductor 103. The end of the resin covering member 104 of the aluminum wire 101 is removed to form a conductor exposed portion 105. On the other hand, the crimp terminal 102 is a male terminal metal fitting, and is formed in a shape as illustrated in the drawing by pressing a copper or copper-alloy metal plate. The crimp terminal 102 includes an electrical contact portion 106 of a rectangular tube shape, a caulking portion 107, and a connection portion 108 which connects the electrical contact portion 106 and the caulking portion 107. In the caulking portion 107, there are formed a mounting portion 109 which is used to mount the conductor exposed portion 105, a conductor caulking piece 110 which is used to caulk the conductor exposed portion 105 mounted in the mounting portion 109, and a covering-member caulking piece 111 which is used to caulk the resin covering member 104 near the conductor exposed portion 105.
In the configuration and the structure described above, a wire-terminal connection portion 118 is formed including a conductor caulking portion 112 which is formed by caulking the conductor exposed portion 105 using the conductor caulking piece 110 and a covering-member caulking portion 113 which is formed by caulking the resin covering member 104 near the conductor exposed portion 105 using the covering-member caulking piece 111. Further, in the conductor caulking portion 112, a non-caulking portion 114 is generated from a relation between a length of the conductor exposed portion 105 and a width of the conductor caulking piece 110. Therefore, the anticorrosion portion 115 (sealing portion) is formed in the wire-terminal connection portion 118 to cover the non-caulking portion 114. The anticorrosion material 117 (sealing material) is dropped from the respective nozzles 116 of two dispensers. Then, the anticorrosion material 117 coated with the dropped anticorrosion material is cured to form the anticorrosion portion 115. Further, silicon rubber is employed as the anticorrosion material 117.
Patent Literature 1: JP 2011-113708 A